This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonThe Internet of the Things (IoT) is evolving rapidly, and its significant impacts
are expected to affect many application domains. Challenges in areas that humans
have been striving to understand, measure, or predict—such as wildlife, healthcare,
or environmental hazards—are likely to be addressed by the time IoT emerges.
The underlying elements of IoT are wireless sensor networks (WSNs),
which consist of a large number of sensor nodes. In the IoT sphere, sensor nodes
represent tangible objects—Things—that monitor changes, collect information,
and eventually send it through the Internet to a recipient party. Inherently, however,
a wireless sensor node relies on limited computational resources with a limited
power source. These undesirable qualities result in a low level of dependability.
This research explores the viability of applying the unfolding network programmability
concepts to overcome survivability obstacles in WSNs and the IoT. In particular,
it examines the viability of software-defined networking (SDN) in network
lifetime maximisation, failure detection, and failure recovery problems in WSNs.
Software-defined networking is a new network programmability concept
that separates the traditionally-tied control and data planes. It offloads the route
computations and management from network devices to a logically centralised
controller. This separation directly leads to better allocation of computational
resources for the network nodes and allows endless orchestration possibilities for
the controller. This thesis proposes an SDN-based solution to increase the survivability
and resilience of WSN environments. Following an approach that conforms
with the centralised nature of SDN environments and considers the limited resources
of the WSN.
A routing algorithm based on A-star was developed for WSNs, then deployed
within an SDN environment to maximise the network lifetime. Apart from finding the path with the lowest energy burden, the algorithm offloads most of
the control traffic from sensor nodes to the controller. This algorithm resulted
in improved resource utilisation among the nodes due to plane decoupling. Additionally,
it increased the lifetime of the network by 22.6% compared to the widely
explored LEACH protocol.
This thesis also investigates different failure detection and recovery practices
in the SDN architecture. The simulation results show that adopting bidirectional
forwarding detection (BFD) with the asynchronous echo mode for WSN
in an SDN environment reduces control traffic for failure detection to between
27% and 48%. The thesis also evaluates the performance of multiple recovery approaches
when adopting the premises of SDN. The simulation results indicate that
path protection, using group tables from the OpenFlow protocol, has a recovery
time up to eight times shorter than the restoration time. The results of the study
reveal that using protection as a failure recovery technique significantly reduces
control traffic overhead